SoConvexDataCache(3) on Linux
The text 309a2b3451ce, as Debian 7 (Wheezy) shipped it.
The SoConvexDataCache class is used to cache convexified polygons. SoConvexDataCache is used to speed up rendering of concave polygons by tessellating all polygons into triangles and storing the newly generated primitives in an internal cache.